Folding loop antenna



May 5, 1931. L. s. BEEBE 1,8049305 FOLDING LOOP ANTENNA Filed April 11. 1929 2 Sheets-Sheet l Inventor": LIoycl 5.1326136, by MW Hi5 Attorney,

May 5, 1931. L. s. BEEBE 1,804,305

FOLDING LOOP ANTENNA Filed April 11, 1929 2 Sheets-Sheet 2 I 5 Inventor;

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Patented May 5, 1931 UNITED STATES PATENT OFFICE LLOYD .S. BEEBE, OF SCOTIA, NEXV YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY,

A CGRPOEATION OF NEW YORK FOLDING noon ANTENNA Application filed April 11, 1929. Serial No. 354,385.

My invention relates to folding loop antenna structures and it has for one of its objects to provide such a structure which is readily foldable into a small space to permit its being carried about with ease and which is of sufficiently rigid construction to preserve with accuracy the electrical characteristics of the antenna through repeated folding operations.

For certain purposes for which portable antennae are employed, and particularly that of measuring field intensity at different points about a common radiating system, it is necessary to employ a loop antenna having a midtap, since by this means, among other reasons, disturbing. currents, such as those due to stray capacity effects and the like, which may affect the accuracy of the. observation may be caused to produce equal electromotive forces between the midtap and the opposite terminals of the antenna, which electromotive forces may be caused to neutralize each other through suitable circuit connections. It is highly desirable to employ an antenna with a fixed midtap and to provide a foldingstructure for the antenna of sufficient rigidly to preserve the electrical center of the antenna at the midtap'notwithstanding repeated folding of the antenna.

A further object of my invention is to provide an antenna possessing the above features and having a frame structure such that the antenna conductor may be wound upon the frame in a continuous solenoid without breaks or interruptions, all of the turns being wound about the frame in parallel relation and equally spaced along the solenoid and all of the turns being of equal length. In this way the antenna may be caused to have a maximum of inductance equally distributed along the solenoid and the two opposite halves may be made to have equal It is desirable-that the two halves of the coil be closely coupled and that the conductors thereof extend in parallel relation since if these conditions do not obtain it may be found that waves traversing the antenna loop will produce different effects in the two halves and thereby afi'ect'the accuracy of the observation.

A further object of the invention is to pro vide a frame structure having the desired rigidity when extended, and which is characterized in that the usual mast is replaced by a small base member, the structure being such that the supporting members of the loop, which are permanently attached together, fall upon each other when the antenna is folded to form a compact column extending in opposite directions from the base member.

A further object of my invention is to pro 'vide a folding frame which is practically free from massive flexible or conductive parts, such as may produce non-uniformity in the electrical characteristics of theantenna and'which is readily foldable in the manner of a double umbrella into a compact column.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, may best be understood by reference to the following description taken in connection with the accompanying drawings in which Fig. 1 represents my antenna in its'extended condition; Fig. 2 represents my antenna in its partially folded condition, and Fig. 3 represents the antenna completely folded.

Referring to Fig- 1 of the drawings it will be seen that the antenna structure 1 comprises a loop conductor wound in a po lygonal solenoid formation upon conductor carrying members 2, one of which is located at each vertex of the polygon, and all of which are supported in parallel relation from the hub structure. The hub structure comprises a pair of members 3 and 3 which are arranged side by side at the central portion of the antenna. I-Iingedly connected to the member 3 are a plurality of supports 4 which extend radially from the central member to one end of each of the different conductor carrying members 2, these supporting members being likewise hingedly connected to the conductor carrying members. Similarly the central member 3 has hingedly connected thereto a plurality of supports 5 which extend parallel with the supports 4 and are likewise hingedly connected to the opposite end of the conductor carrying members 2.

The supporting members 4 and 5 which are connected to a conductor carrying member 2 are hingedly connected thereto for outward movement and are secured against inward movement by means of straps 3. These straps constitute braces between the respective supportingmembers and the carrying member, and are suitably suspended from the belt which extends through each of the bifurcated end portions of the carrying members and the end of the corresponding supporting member thereby to constitute a pivot or hinge, by means of which the supporting member is attached to the carrying member. Similarly the members 4 and 5 are hingedly attached to the respective central members for inward movement and are secured against outward movement by braces 6, one of which is attached to the outer surface of eachof the supports 4 and 5 and extend beyond the inner end thereof to engage the outer surface of the centraljmember. By means of the straps 7 and braces 6 any sidewise move ment or swaying of any portion of the loop is avoided. 1 a

The central members 3 and 3 are locked together by means. of a bayonet joint which is best shown in Fig. 2, this oint comprising a socket member 8 which is attached to the central member 3 and a member 8 which projects from the central member 3" to cooperate with the socket member 8. A tooth 9 projects from the member 8 and is arranged to cooperate with an opening 10 in the socket member 8, thereby to lockthe central members 8 and 3' in fixed spaced relation. Either or both of the members Sand 8 may be made rotatable in order to provide for locking and unlocking of the central members.

The conductor 1 is wound upon the carrying members 2 from one side of the carrying members as at the terminal 11 progressively across the carrying members turn by turn to the opposite terminal member 12. Thus the antenna comprises a uniformsolenoid extending across the carrying members. The conductor is secured to each carrying member by means of strips 13 which are attached as by means of screws to the outer surface of the carrying members to securely clamp the conductorsrbetween the strips and the conductor carrying members.- A midtap may be provided upon the center turn of the loop as at 14C.

It will thus be seen that all of the turns of the conductor are of thesame length and are parallel, that the two halves of the antenna are electrical equivalents, and that the electrical center of the antenna may be maintained at the tap 14;. 4 The supports 4 and 5 are rigid thereby firmly to hold the loop in shape when it is extended and are sufficiently light to obviate non-uniformity resulting from massive material located within the field of the antenna. Thesemembers and similarly the hub structure and carrying members 3 are comprised of suitable non-conducting material such as wood or a phenolic condensation product;

To fold the antenna it is preferable, to avoid entangling and kinking of the wires, to place it in a horizontal position, as shown in Fig. 2, and then to unlock and separatethe central members as by grasping theknobs 15 and 15 and pulling them outwardly. The supporting members 4 and 5 then fall upon each other into a column extending between the central members 3 and 3', as shown in Fi 8 the carr ing members extendin in a: 7 .l b

the direction of the column at the middle portion thereof. The conductors then fall in loose loops fixed at the middle of the column and suspended loosely along the column toward the central members. Preferably the conductor 1 is multiple strand to provide a degree of flexibility such as to prevent the con ductor from assuming a definite set, kinks, etc. when folded. I

For the purpose of supporting the antenna structure a, suitable base member 16 is attached to one of the members 13.- Inthis way any interruption of the, continuity of the loops-and any loose coupling between the two halves ofthe loop which may result from separating theaconductors sufiiciently to permit the use of a mast projecting between the conductors is avoided.

While I have shown a particular embodiment of my invention, it will of course be understood that various modifications may be made, and I intend by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1.- A folding antenna structure, comprising a pair of central members arranged side by bers, means attached to the central members for supporting said conductor carrying members about the central. members in parallel relation, a loop conductor wound upon said carrying members to form a solenoid, and

-means cooperating with the central members to cause the supporting means tofall into a column extending from the carrying members outward in opposite directions toward the central members when the are separated. r

2. A folding antenna-structure, comprising a pair of central members arranged side central members by side, a plurality of conductor carrying members, a loop conductor carried by said members, a plurality of supporting members extending radially from each of said central members, each of said supporting'members being hingedly connected to the respective central, member and to one of said carrying members, and each carrying member being supported by a radial member extending from each central member, whereby said central members may be separated causing the supporting members to fall upon each other to form a column extending between the two central members.

3. A folding antenna frame, comprising a hub structure, a plurality of conductor carrying members arranged about said hub structure, a pair of supporting members extending between opposite points on each of said carrying members and said hub structure and hingedly connected to said carrying members for outward movement, said supporting members being rigidly secured to each other by said hub structure, and detaching means at the hub structure whereby the supporting; members connected to opposite points on the carrying members are movable outward thereby to cause said supporting and carrying members to fall upon each other in column.

1-. A folding antenna structure, comprising a pair of central members arranged side by side, a plurality of conductor carrying members, a loop conductor carried by said members, a plurality of supporting members extending radially from each of said central members to said carrying members, each carrying member being supported by a supporting member attached to each of said central members, each supporting member being hingedly attached to the carrying member for outward movement from the normal position and secured against inward movement therefrom, and attached to the central member for inward movement from the normal position and secured against outward movement therefrom whereby said central memhere may be separated causing said supportin 9; members to fall in a column between the central members.

5. A folding antenna structure, comprising a pair of central members arranged side 'by side, a plurality of conductor carrying members, a loop conductor carried by said members, a plurality of supporting members extending radially from each of said central members, each of said supporting members being hingedly connected to the respective central member and to one of said carrying members, and each carrying member being supported by a radial memberextending from each central member, whereby said central members may be separated causing the supporting members to fall upon each other to form a column. extending between the two mntral members, spacing means between said central members comprising a socket attached to one member and a projecting member secured to the other member and arranged to cooperate with said socket to secure said members together in fixed space relation, whereby when said In witness whereof, I have hereunto set my hand, this 10th day of April, 1929.

LLOYD S. BEEBE. 

